Patent Application
20140246526
The present invention relates to a drum-type wood chipper and more particularly to an apparatus and method for handling air within a drum-type wood chipper.
Drum-type wood chippers of the kind typically used to chip tree stems, tree limbs, branches, brush, wood scraps and other wood debris often include a housing having an internal chamber in which a chipper drum is supported for driven rotation. The drum carries a plurality of cutting knives spaced about its perimeter which, when wood debris is fed into the chamber, reduce the limbs and such to chips. The chips are discharged through an outlet in the chamber and transported by their momentum along a discharge chute for collection, typically in a chamber or bin, such as that provided on a towing vehicle used to transport the chipper.
As the type of wood and size of the chips can vary, it is not uncommon for some of the chips to be too light such that they have insufficient momentum to travel the length of the discharge chute and collect in the chamber. One proposed solution to the problem has been to add fan blades to the side of the drum in order to generate a flow of air in the chipping chamber to help carry the chips along. The flow of air, however, is difficult to control and in some cases an undesirable backflow develops wherein dust and light debris is discharged through the material inlet.
Another proposal has been to equip such chippers with a discharge fan external to the housing that is driven off the drum shaft and is coupled by a hose to the discharge chute for creating an air flow in the chute downstream of the outlet which acts to draw and carry the chips along and into the collection bin. While such external fan devices are effective at entraining the chips, there is not always room enough on the chipper apparatus to accommodate the mounting of the external fan assembly. Further, the necessity of an additional air hose from the fan to the discharge chamber detracts from the appearance of the chipper apparatus, is prone to damage, and adds to the maintenance and cost of the apparatus.
One particularly effective drum-type wood chipper is fitted with a discharge fan internal to the housing of the chipping chamber, but isolated from this chamber by a circumferentially extending chamber wall. Air is drawn into the fan chamber through an inlet communicating with the air outside the chipping apparatus and discharged at a high velocity through an outlet of the fan chamber. A baffle separates the outlet of the fan chamber from a discharge area for the material being chipped in the drum. Air entering an exit chute from the fan chamber joins a flow of chips from the chipper and entrains the chips to carry them out of the material exit chute. The baffle prevents the stream of air from the fan chamber from flowing back into the chipping chamber. Although a marked improvement, this design does not overcome the problems of “blowback” from the drum chamber. Blowback occurs when the spinning of the chipper drum in the chipping chamber forces air out in all directions thus blowing air, chips and dust out the material infeed toward the operator.
The present invention provides a drum-type wood chipper having a discharge fan with an inlet that draws air into the fan from within the drum chamber and an outlet that exhausts air to assist in propelling wood chips from the chipper. The chipping drum and the discharge fan may be disposed within a common housing. Further, the discharge fan may be carried on the chipping drum shaft so that it rotates with the drum.
In one embodiment, the wood chipper has a housing with an internal chipping chamber defined by one or more peripheral walls. The housing may include a material inlet in a peripheral wall to permit wood debris to be fed into the chipping chamber. The housing may also include an outlet in a peripheral wall to allow chipped material to exit the chipping chamber. The wood chipper may have a discharge chute coupled to the outlet to direct the flow of chipped material from the wood chipper.
In one embodiment, the wood chipper includes a base at the bottom of the chipping chamber that separates the chipping chamber into a drum chamber and a fan chamber. The chipping drum may be rotatably mounted inside the drum chamber on a shaft. The discharge fan may be rotatably mounted inside the fan chamber, also supported by the shaft. The fan chamber may be separated from the drum chamber by a partition wall. The fan chamber may receive air from the drum chamber through a drum chamber air inlet in the partition wall, and also from an external air inlet opposite said drum chamber air inlet. In operation, the discharge fan may create air flow in the direction from the drum chamber inlet and the external inlet toward the outlet and the discharge chute.
In one embodiment, the fan in the chipping apparatus includes a disc with blades affixed to the side of the disc facing the drum chamber inlet. Additionally or alternatively, the fan also has blades affixed to the side of the disc facing the external air inlet.
Another embodiment includes a deflector attached to the peripheral wall of apparatus. The deflector may be installed in the transition area between the discharge outlet and the peripheral wall. In use, the deflector may help to increase the amount of air flow out to the discharge.
Further embodiments include an air entrainment system for a wood reduction apparatus. In this embodiment, the system includes a fan chamber internal to the housing and separated from the drum chamber by a partition wall. A cutout in the partition wall allows for fluid communication between the drum chamber and the fan chamber. An external air inlet allows ambient air into the fan chamber from outside the housing. The fan draws air from the drum chamber and from outside the housing and the air moves toward the discharge end of the apparatus.
The wood chipper may further provide a common shaft to support both the fan and the chipping drum. The shaft allows conjoint rotation of the fan and the drum.
In another aspect, the present invention provides a method for reducing wood debris in a wood chipper. The method generally includes the steps of providing a wood chipper having a material inlet, a drum chamber, a fan chamber and a discharge chute; rotatably disposing a chipping drum in the drum chamber; rotatably disposing a discharge fan in the fan chamber; providing an air passage from the drum chamber to the fan chamber; and rotating the chipper drum and the fan so that air is drawn into the fan chamber from the drum chamber and expelled through the discharge chute. The method may further include the steps of providing an air passage between the fan chamber and the exterior, and operating the fan so that air drawn into the fan chamber from the drum chamber and the exterior.
The present invention provides a simple and effective system that can effectively manage blowback while providing air flow to assist in discharging chipped materials from the wood chipper. The system is relatively inexpensive to implement and operate as it can be contained within the drum chipper housing and be driven by the power source for the drum chipper. The desired air flow can be easily tuned by controlling various aspects of the system. For example, the size, shape and configuration of the fan, fan blades, drum chamber air inlet, external air inlet baffle. In those embodiments that incorporate a deflector in the transition area, the deflector may help to increase the amount of air flow out the discharge.
These and other objects, advantages, and features of the invention will be more fully understood and appreciated by reference to the description of the current embodiment and the drawings.
Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention may be implemented in various other embodiments and of being practiced or being carried out in alternative ways not expressly disclosed herein. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components.
An apparatus for reducing tree stems, tree limbs, branches, brush, wood scraps and other wood debris to wood chips in accordance with one embodiment of the present invention is shown generally as 10 in
For purposes of disclosure, the present invention is described in connection with a drum-type wood chipper that is intended to be towed by a vehicle. In this embodiment, the wood chipper 10 has a support frame 12 mounted to a set of wheels 14 and has a coupling 16 at its forward end for coupling the wood chipper 10 to a towing vehicle (not shown). While any of a number of towing vehicles may be suitable, the towing vehicle may be of a type having a collection bin that is open at the back to receive the wood chips discharged from the wood chipper 10, as will be explained further below. Although described in connection with a drum-type chipper, the present invention may be implemented in other types of wood reduction machines that might benefit a discharge fan configured to draw air through the infeed to address “blowback” or other similar problems.
The wood chipper 10 of the embodiment illustrated in
As noted above, in this embodiment, the housing 18 is mounted to the frame 12 and includes an internal chipping chamber 20 in which a chipping drum 22 is supported for driven rotation about an axis A, as shown best in
As best shown in
The drum 22 of this embodiment is rotated at a high velocity in a downwardly, counterclockwise direction as viewed in
The apparatus 10 includes a discharge chute 52 coupled at a receiving end 54 thereof to the housing 18 in communication with the material outlet 50 for receiving and guiding the wood chips expelled from the chipping chamber 20 outwardly of the housing 18 to an opposite discharge end 56 of the chute 52, where they may be expelled into an adjacent collection bin, such as that on the towing vehicle.
To provide airflow through the chipping chamber 20 toward the discharge chute 52, an entrainment system 58 in provided. The entrainment system 58 of this embodiment includes a base 21 (as best shown in
Referring to
As shown in
Although described in connection with a fan 70, 170 having blades 72 on the drum-facing side of body 71 or with blades 172 on both sides of the body 171, the fan may have essentially any configuration that allows sufficient air to be drawn from the drum chamber 23 (and optionally the exterior) and expelled through the discharge chute 52. The fan 70, 170 may be, for example, an axial fan, a centrifugal fan or a cross-flow fan. The fan 70, 170 may incorporate essentially any type of impeller or blade arrangement. For example, in one embodiment, the disc-like body may be eliminated and the blades may extend radially outward from a central axis.
The fan chamber 60 has an air outlet 76 adjacent the material outlet 50 of the chipping chamber 20. The receiving end 54 of the discharge chute 52 communicates with the air outlet 76. A baffle 78 extends from the partition wall 26 between the chipping chamber 20 and the fan chamber 60 into the discharge chute 52 between the material outlet 50 and the air outlet 76, dividing the receiving end 54 into a chip side 79 communicating with the chipping chamber 20 and an air side 80 communicating with the fan chamber 60.
Referring to
In operation, the fan 70, 170 rotates conjointly with the chipping drum 22 about the shaft 38 and draws air into the fan chamber 60 from the external inlets 66 and from the drum chamber inlet 67. The air flow created by the fan 70, 170 is a high velocity flow sufficient to overcome the negative air flow created by the spinning drum 22 and move air toward the discharge chute 52 and away from the material inlet 34. Wood chips that were reduced in the chipping chamber 20 are drawn to the discharge chute 52 at the receiving end 54 of the apparatus 10. As the wood chips are drawn by the air flow created by the fan 70 toward the material outlet 50 and discharge chute 52, the wood chips remain on the chip side 78 of the baffle and become entrained with the air flow create by the fan 70 once they pass the baffle 78.
As noted above, the discharge fan may be essentially any type of fan capable of moving air through the system. For purposes of illustration, examples of alternative embodiments incorporating centrifugal fans are shown in
Referring now to
Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “forwardly,” “rearwardly,” “inner,” “inwardly,” “outer” and “outwardly,” are used to assist in describing the invention based on the orientation of the embodiments shown in the illustrations. The use of directional terms should not be interpreted to limit the invention to any specific orientation(s).
The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the invention or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element(s) of the described invention may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Further, the disclosed embodiments include a plurality of features that are described in concert and that might cooperatively provide a collection of benefits. The present invention is not limited to only those embodiments that include all of these features or that provide all of the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.
